1. Field of the Invention
The present invention relates to an apparatus and method of use for measuring the geometry of a foot. More particularly, the present invention further relates to an apparatus having a specially formed foam impression block. The present invention further relates to such an apparatus having a specially designed container. Moreover, the present invention further relates to methods of using such an apparatus for measuring the plantar contour and the instep of a foot.
2. Description of the Related Art
A number of methods currently exist to measure the geometry of a foot. These methods include plaster casting, optical scanning, contact sensor measurement, as well as foam impression measurement.
The optical scanning methods and contact sensor measurement methods utilize expensive equipment. These methods provide an accurate and complete measurement of the foot. But, the size, expense and complexity of the equipment necessary for these methods makes them not suitable for use in all locations.
Plaster casting methods require the measurement to be performed by a person other then the one being measured. This method provides an accurate and complete measurement of the foot but can be very messy and time consuming. Thus, plaster casting methods are not suitable for use in a person""s home or by one""s self.
Foam impression measurement methods and apparatus utilize an easily deformable foam block. A person steps onto the block, thus crushing the foam in the locations of higher pressure. In this manner, the foam block deforms in the approximate shape of the persons"" plantar contour. The prior art produces a sub-optimal characterization of the foot for a number of reasons. First, the foam block is uniform in thickness from heel to toe. This causes the toes to be forced upward as the foot is pressed into the foam because the toes of the foot have substantially less pressure on them than the region of the foot from the heel to the metatarsal heads. Forcing the toes upward can cause a number of problems including, hyperextension of the plantar fascia, lowering of the correct arch height, and improper measurement of the forefoot and heel. Second, the prior art does not provide an accurate baseline for placement of the foot. Thus, it provides for a poor definition of the centerline of the foot that results in improper centering of the foot in the shoe. Next, the prior art a does not provide for measurement of the instep or of the upper forefoot. Moreover, placement of the foot in prior art impression blocks is not intuitive.
In the manufacture of custom insoles, the use of the plaster casting and foam impression methods described above also require the use of a scanning system. The scanning system in this instance, however, is centrally located at, for instance, a custom insole manufacturing facility. The scanning system may act directly on the negative impression within the foam or plaster. Scanning systems that act directly on negative impressions are known in the art. These laser-scanning systems consist of a laser with a line generating optic. The laser projects a line at a known incident angle onto the negative impression. A camera is used to read the position of the laser line on the negative impression. Alternatively, the scanning system may act on a positive plaster model made from the negative impression within the plaster or foam. Scanning systems that act directly on the positive impressions are also known in the art. One such scanning system, provided by U.S. Pat. No. 4,876,758, specially constructed array of pin-like sensors. In either circumstance, the scanning system is used to digitize the measured contour. The digitized contour is provided to a computer controlled milling machine. The milling machine uses the digitized information to manufacturing a custom insole matching the digitized contour. Accordingly, the apparatus and methods of the present invention provide for cheaper and easier means to provide custom manufactured insoles to a customer. Moreover, the present invention provides a foot measurement apparatus and method that overcome the limitations set forth above.
The present invention provides an apparatus for measuring a person""s plantar contour and/or instep. The apparatus has a foam impression block with a toe thickness and a heel thickness; provided that the toe thickness is less than the heel thickness.
The apparatus also has a first holding case wherein the block is disposed. The case has an opening for accessing the block. The opening is shaped to approximate the shape of either a left foot or a right foot.
The apparatus also has a compliant medium with a plurality of straps having sizing graduations thereon. The compliant medium is placed on the block and acts to prevent the block from adhering to the user""s foot. The straps are adapted to wrap around the foot and the graduations are used to indicate the height of the instep.
The present invention also provides a method for measuring a person""s plantar contour. The method involves the steps of placing the plantar contour of the person""s foot over a foam impression block with a toe thickness and a heel thickness; provided that the toe thickness is less than the heel thickness, and pressing the plantar contour into the block to deform the block.
Furthermore, the present invention provides a method for measuring a person""s plantar contour. The method involves the steps of placing the plantar contour of the person""s first foot over a foam impression block disposed within a first case; aligning the first foot such that the person""s toes are over the toe thickness and the person""s heel is over the heel thickness provided that the toe thickness is less than the heel thickness; and pressing the plantar contour through the opening into the block to deform the block.
Alternatively, the present invention acording to another embodiment includes a method involving the steps of placing the plantar contour of the person""s first foot over a foam impression block disposed within a first case; aligning the first foot such that the person""s toes are over the toe thickness and the person""s heel is over the heel thickness provided that the toe thickness is less than the heel thickness; pressing the plantar contour through the opening onto the compliant medium and into the block to deform the block; wrapping at least one strap around the instep of the foot perpendicular to the length of the foot; and noting the perimeter indicated by the graduations on each strap.